Fiber-forming blend of acrylonitrile polymers



Patented Oct. 12, 1954 FIBER-FORIWING BLEND OF ACRYLO- NITRILE POLYMERS-George E. Ham and Alfred B. Graig, Dayton, Ohio, assignors to TheChemstrand Corporation, Decatur, Ala., a corporation of Delaware NoDrawing. Application March 1, 1952, Serial No. 274,496

7 Claims.

This invention relates to new and valuable acrylonitrile polymers. Moreparticularly, the invention relates to fiber-forming acrylonitrilepolymers, which are dyeable by conventional dyeing procedures utilizingacid dyestuffs, and to new and useful monomers which are copolymerizablewith acrylonitrile polymers.

This application is a continuation-in-part of our copending applicationSerial No. 206,916, filed January 19, 1951.

It is well-known that polyacrylonitrile and copolymers of acrylonitrileand other polymerizable mono-olefinic monomers, such as styrene andvinyl acetate are excellent fiber-forming compositions. It is alsowell-known that the copolymerized monomer may influence the chemical andphysical characteristics of the resultant copolymer.

Accordingly, the primary purpose of this invention is to providecomonomers which will produce superior fiber-forming polymers having thedesirable physical properties of synthetic polyacrylonitrile fibers andat the same time have the desirable chemical properties of naturalfibers. A further object of the invention is to provide differentpolymeric substances suitable for improving acrylonitrile polymers byblending, especially for the purpose of developing dye aflinity. Anotherobject of the invention is to provide a new class of monomers which arecopolymerizable with acrylonitrile to produce superior fiberformingpolymers. Other objects and advantages of the present invention will beapparent from the description thereof hereinafter.

In accordance with this invention it has been found that variousN-heterocyclic nitrogen compounds containing olefinic functions may beccpolymerized with acrylonitrile to develop improved dye-receptivity.Suitable N-heterocyclie monomers for copolymerization with acrylonitrileare the pyridines which contain olefinic unsaturation in a side chainand have the general formula:

wherein R. is an alkenyl radical selected from the group consisting ofvinyl, allyl, and methallyl, which radical may be attached to either the2, 3, or 4 carbon of the heterocycle. Examples of suitable monomershaving the above general formula are: allyl nicotinate, vinylnicotinate, allyl isonicotinate, vinyl-isonicotinate, methallylnicotinate, allyl picolinate, methallyl picolinate, etc.

In the preparation of copolymers of the above unsaturated cycliccompounds and acrylonitrile it has been found desirable to use from 1 to15% of the N-heterocyclic compound and to polymerize in the presence offrom 85 to 99% of acrylonitrile. It has also been found that the aboveN-heterocyclic monomers may be introduced into the fiber spinningpolymers by a blending technique, and in accordance with this method theN-heterocyclic compound is polymerized by itself or in the presence ofother monoolefinic monomers. For this purpose the other monomers may bevinyl chloride, vinyl acetate, acrylonitrile, styrene,methacrylonitrile, methyl methacrylate, vinylidene chloride, diethylmaleate, dimethyl fumarate, or homologues of these compounds, and ingeneral, any olefinic monomer which is copolymerizable with theN-heterocyclic monomers. The polymers of the N-heterocyclic compoundsfor use in the blending procedures will be polymers of 3-0 to 100% ofthe N-heterocyclic monomers and up to 70% of the other monomer. In theuse of the blending technique it is desirable to use a sufficientquantity of the blending polymer so as to provide from 1 to 15% of thecyclic monomer in polymerized form in the fiber spinning polymer.

When the blending technique is used in accordance with this inventionthe principal polymer may be polyacryloni-trile, or it may be acopolymer of acrylonitrile with minor proportions of other monomerscopolymerizable therewith, for example, vinyl acetate, styrene,methacrylonitrile, vinyl chloride, methyl acrylate, diethyl fumarate,dimethyl maleate, or homologues thereof. At least of the acrylonitrileshould be used and preferably in excess of The blends will utilize from50 to 99% of the principal copolymer and from 1 to 50% of the blendingpolymer depending upon the amount of N-heterocyclic monomer in theblending polymer.

The blends may be prepared by a wide variety of methods, but for optimummixing it is desirable to perform the blending when both are dissolvedin a common solvent. Suitable solvents for practicing the dispersionwill be the same solvents from which the blended polymer is spun intofibers, for example, N,N-dimethylformamide, ethylene carbonate, gammabutyrolactone, alphacyanoacetamide, N,N-dimethylacetamide, maleicanhydride, or other solvents known to have the property of dissolvingpolyacrylonitrile and high acrylonitrile copolymers. The copolymers ofacrylonitrile and the above described N-heterocyclic monomers, theblending polymers of the N-heterocyclic monomers, and the principalpolymer with which the blending polymer is mixed may all be prepared bythe so-called emulsion or suspension polymerization method in aqueousmedium. These polymerizations usually require a free radical type ofcatalyst and emulsifying or dispersing agents. The methods ofpreparation preferably utilize a mixed monomer addition techniquewhereby the monomers are mixed in the proportions desired in theultimate copolymer and added continuously to the reaction mediumthroughout the course of the reaction. The various details of thepolymerization method should be so selected in order to produce polymersor copolymers of substantially uniform physical and chemicalcharacteristics.

The reactions may be catalyzed with a wide variety of free radicalproducing substances, for example, the peroxy compounds, and preferablythose which are water-soluble, for example, hydrogen peroxide, sodiumperoxide, potassium persulfate, calcium percarbonate, and other salts ofperoxy acids. In the preparation of some of the copolymers ofacrylonitrile and the N-heterocyclic monomers, the ace catalysts areoften found to be effective. Suitable azo catalysts are ace-2,2-diisobutyronitrile and dimethyl-2,2' azodiisobutyrate, 2,2'-azobis(ZA-dimethylvaleronitrile), and 2,2'azodiisobutyramide. In addition,diazoaminobenzene and its derivatives may be employed as catalysts. Theazo catalysts are also found to be desirable in the preparation of theblending polymers, and particularly where a substantial proportion ofthe polymer is the N- heterocyclic monomer. Ihe principal polymer forblending is preferably prepared in the presence of an alkali metal saltof peroxysulfuric acid.

The emulsion or dispersing agents used in the practice of this inventionmay be any compound which has both a hydrophilic and a hydrophobicradical. Suitable emulsifying r dispersing agents include the commonsoaps, such as sodium stearate and other alkali metal salts of highmolecular weight, carboxylic acids and mixtures thereof as obtained bythe saponification of animal and vegetable fats, the salts of sulfonatedhydrocarbons, for example the alkali metal salts of sulfonatedparafiins, sulfonated naphthalenes, and sulfonated alkylbenzenes, thesalts of formaldehyde condensed sulfonic acids and particularly thesodium salt of formaldehyde condensed alkylaryl sulfonic acids, thesalts of triethanolamine and other amino soaps, and alkali salts ofsulfuric half esters of fatty alcohols.

If desired, the various classes of copolymers may be prepared, by theredox method in the presence of sulfur dioxide, sodium bisulfite, sodiumthiosulfate, and other compounds containing sulfur in the lower valentstage. The use of the redox system usually permits operation at lowertemperature and results in the formation of copolymers of high molecularweight.

' The polymerizations may also be conducted in the presence of molecularweight regulators, for example, t-dodecyl mercaptan, thioglycolic acid,thiourea, mercaptobenzothiazole, and carbon tetrachloride. These andother well-known regulators prevent the formation of very high molecularweight polymer increments and tend to induce a more uniform size ofpolymer molecules.

The polymerization reactions are preferably initiated by heating areactor containing water to a temperature under which the polymerizationis to be conducted. The aqueous medium is then charged with a catalystwith at least some of the catalyst, dispersing agent, regulator, andredox agent, if they are to be used. The reaction medium is thenvigorously agitated by a mechanical stirrer or by tumbling the reactor.When all of the proper conditions for polymerization exist in thereactor, the monomers either pre-mixed or in separate streams are addedgradually in the proportions desired in the copolymer. It is desirableto add the monomers at a rate substantially that in which they arecombining in the copolymer. in this manner substantially uniformreaction conditions are maintained in the vessel. Similarly, thecatalyst, emulsifying agent, and other reagents are added gradually orintermittently throughout the course of the reaction so as to maintainprecisely or approximately a uniform concentration of the essentialreagents within the reactor at all times. The reaction is then conducteduntil all the predetermined lot of monomers is charged. At this pointthe reaction is terminated.

In the practice of this invention it is desirable to maintainsubstantially uniform reaction conditions. This may be done by addingthe monomers at a fixed constant rate, or by maintaining the reactiontemperature at a substantially constant level. A preferred method ofconducting the reaction utilizes operation at the reflux temperature,and when this method is used it has been found desirable to add themonomers at a varying rate so a to maintain a constant temperature ofreflux within the vessel. Operation in this manner will maintain thesame quantity and proportion of monomers in the reaction vesselthroughout the entire reaction, but the proportion of monomers willusually be somewhat different from the proportions which arepolymerizing to form the copolymers. Thus, in order to maintain asubstantially uniform proportion in the polymer it is desirable todetermine the relationship of the proportions in the vessel to theproportions in the resulting copolymer. By initially charging thereaction vessel with the proportions of monomers which are required inthe vessel to form the copolymer of desired proportions, and by addingthe monomer throughout the reaction in the proportions desired in thecopolymer and maintaining operation at constant reflux temperature, thecopolymers very uniform in chemical and physical properties will beobtained. It will be apparent that since all of the predetermined lot ofmonomers has been added, the proportion of monomers in the vessel willchange due to the depletion of the more active monomer. At this point itis desirable to interrupt the reaction by removing one of the essentialconditions of operation, for example, by lowering the temperature, bydestroying the catalyst or by rapidly steam distilling oif unreactedmonomers.

Upon the completion of the polymerization an emulsion or a suspension ofsolid polymer in the aqueous medium will be obtained. Although some ofthese dispersions can be filtered, many are stable emulsions which mustnecessarily be precipitated by the addition of a suitable reagent, forexample, aluminum sulfate, sodium chloride, or another electrolyte, oran alcohol, such as ethanol, or by freezing, rapid agitation, or otherwell-known means for breaking emulsions.

The solid polymers are substantially free of moisture or can be made soby drying in any conventional oven or by other means known to the art.

The copolymers' of acrylonitrile and the heterocyclic'nitrogen monomersand the blends of nondyeable acrylonitrile polymers with minor proparedin this manner will be found to have physical properties greatlysuperior to all natural fibers and most synthetic fibers, and at thesame time have dye-receptivity comparable or superior to natural fibers,such as wool.

Furtherdetails of the preparation of the new monomers and thepreparation and use of the new copolymers from said monomers are setforth with respect to the following specific illustrative examples.Unless otherwise specified all parts and percentages are by weight.

Example I v A solution of 40 parts of sodium hydroxide in 50 parts ofwater and 112 parts of allyl alcohol was cooled to approximately '10 to0 C". The solution was stirred and maintained at low temperature with anice bath. 89 parts of nicotinyl chloride hydrochloride was slowly addedto the stirred solution. When all the chloride had been added, thesolution was allowed to warm to room temperature. The slurry formed wasextracted with ether and the extract dried over sodium sulfate. Afterremoving the solvent and excess allyl alcohol, 6.3 parts of allylnicotinate distilled at 91-2 C. at 3 mm. pressure.

Example II A mixture of 89 parts of isonicotinyl chloride hydrochloride,135 parts of allyl alcohol, and 40 parts of pyridine was refluxed forfive hours. After cooling the mixture to room temperature, 150 parts ofwater were added and the solution was made basic with potassiumcarbonate. This solution was then extracted repeatedly with benzene andchloroform. All the extracts were combined and dried over sodiumsulfate. After removing the solvents by distillation, 35 parts of allylisonicotinate distilled at 94-7 C. at 4 mm. pressure.

Example III A mixture of 89 parts of picolinyl chloride hydrochloride,135 parts of allyl alcohol, and 40 parts of pyridine are refluxed for aperiod of hours. After cooling the mixture, 150 parts of water are addedand the solution is made basic with potassium carbonate. The resultantsolution is then extracted with Ibenzene and chloroform and the extractscombined and dried over sodium sulfate. The added solvents are thenevaporated and the allyl picolinate is recovered by distillation.

Example IV Employing the conditions of Example III methallyl picolinateis prepared when methallyl alcohol is employed in place of allylalcohol. The methallyl picolinate is recovered by distillation.

Example V Nicotinic acid is vinylated by the gradual introduction ofacetylene into a suitable solution of nicotinic acid in an inert diluentcontaining mercuric acetate. The vinyl nicotinate is thereafterseparated by fractional distillation.

6 Example VI Example VII The copolymer of Example VI was dissolved inN,N-dimethylacetamideto give a 12% solution. The solution was spun intoa mixture of 60% N,N-dimethylacetamide and 'i0% water, using a 30 hold(.005 inch) spinneret and the fibers thus formed were washed with water,continuously dried on a heated drum, and steam-stretched 261 Theresulting fibers were almost colorless, and possessed a tenacity of 3.0gm./denier and an elongation of 2 to 7%. After heating for /2 hour at300 F., the fibers wer almost unchanged in color. Skeins of the fiberwere readily dyed to a deep shade upon immersion in a dye-bathcontaining 2% Wool Fast Scarlet dye and 10% sulfuric acid (based on thefiber weight) for 2 hours at C.

Example VIII A mixture of 92 parts of acrylonitrile, 8 parts of allylisonicotinate, and 0.2 part t-dodecyl mercaptan was added continuouslywith rotary agitation to a solution of 0.1 part of a sodium salt of aformaldehyde condensed naphthalenesulfonic acid dissolved in 170 partsof distilled water contained in a round-bottomed flask over a 2.5 hourperiod at 80 C. After allowing the mixture to reflux for /2 hour,unreacted monomer was steam-distilled and the mixture was filtered,washed with water, and dried. A yield of 78.5% of the copolymer wasobtained (specific viscosity in 0.1 dimethylformamide of 0.202) 'Filmscast from the copolymer in the usual manner were dyed to deep shadeswith acid dyes.

Example IX A mixture of 3.2 parts of allyl nicotinate, 36.8 parts ofacrylonitrile, 0.2 part of azo-diisobutyronitrile, 0.04 part of sodiumsalt of a formaldehyde condensed naphthalenesulfonic acid, and parts ofdistilled water was heated in a pressure bottle for six hours at 72 C.in a tumbling oven. The copolymer was filtered, washed with alcohol, anddried. A yield of 89.3% of the coplymer was obtained (specific viscosityin 0.1% dimethylformamide of 0.200). Films cast from the copolymer inthe usual manner were dyed to deep shades with acid dyes.

It is to be understood that changes and variations may be made withoutdeparting from the spirit and scope of the invention as defined in theappended claims.

We claim:

1. A fiber-forming blend of (A) a polymer of a monomeric substance ofwhich acrylonitrile is at least 80% by weight of its pclymerizablecontent and up to 20% of another polymerizable mono-olefinic monomercopolymerizable there- 7 with and (B) a polymer of at least 30% of acompound having the general formula wherein R is an alkenyl radicalselected from the group consisting of vinyl, allyl and methallyl and upto 70% of another polymerizable mono-olefinic monomer copolymerizabletherewith.

2. A fiber-forming blend of 50 to 99% of (A) a polymer containing byweight in the polymer molecule at least 80% of acrylonitrile and up to20% of another polymerizable mono-olefini'c monomer, and one to 50% of(B) a polymer containing by weight in the polymer molecul at least 30%of an N-heterocyolic compound having the general formula:

wherein R is an alkenyl radical selected from the group consisting ofvinyl, allyl and. methallyl and up to 701% of another polymerizablemono-olefinic monomer, said polymer (B) being the only source of theN-heterocyclic compound.

3. A fiber-forming blend as defined in claim 2 wherein theN-heterocyclic compound is allyl nicotinate.

4. A fiber-forming blend as defined in claim 2 wherein theN-heterocyclic compound is allyl iso-nicotinate.

5. A fiber-forming blend as defined in claim 2 wherein theN-heterocyclic compound is allyl pieolina-te.

6. A fiber-forming blend as defined in claim 2 wherein the N-heterocyclio compound is vinyl nicotinate.

'7. A fiber-forming blend as defined in claim 2 wherein theN-heterocyclic compound is methallyl picolinate.

References Cited in the file of this patent UNITED STATES PATENTS Number

1. A FIBER-FORMING BLEND OF (A) A POLYMER OF A MONOMERIC SUBSTANCE OFWHICH ACRYLONITRILE IS AT LEAST 80% BY WEIGHT OF ITS POLYMERIZABLECONTENT AND UP TO 20% OF ANOTHER POLYMERIZABLE MONO-OLEFINIC MONOMERCOPOLYMERIZABLE THEREWITH AND (B) A POLYMER OF AT LEAST 30% OF ACOMPOUND HAVING THE GENERAL FORMULA